On Ethylene Polymerisation with Aluminium and Scandium Complexes: DFT and Post-HF Calculations

The performance of Density Functional Theory (DFT) methods in predicting ethylene polymerisation and/or oligomerisation activity in selected aluminium and scandium based complexes was studied using both DFT and post-Hartree-Fock CCSD(T) calculations. Whereas previous reports have drawn attention to the underestimation of the barrier for the beta-hydrogen termination process for a few aluminium based species, we found that the same holds for the corresponding scandium complexes. New, however, is the observation that apart from underestimating the energy barrier connected to beta-hydrogen termination, the insertion of ethylene is also several underestimated by the DFT methods applied compared to post-Hartree-Fock calculations up to the CCSD(T) level